Messed Up Header.php

I tried editing my website (which uses the Virtue theme by Kadence) and I have no clue what I’m doing. I tried going all web coder commando on it, and inserted a line of code into what I thought could possibly be line 72 under the Editor tool for header.php. I was trying to widen my banner image to the width of the browser. But now my website it totally broken. Is there a way to download the original header.php code again? And if so, do you know a way I could then edit line 72 to make my banner image the width of the website?